Road paving binders

Abstract

This invention provides for novel road paving binder compositions and the method of making them. One embodiment is a road paving binder composition of a storage stable blend of a sulfonated, unhydrogenated random copolymer of styrene and butadiene having a sulfonation level of from 1 to 100 meq S03H/100 g of polymer and a sulfonated asphalt. Another is a method of making a storage stable polymer modified asphalt composition by combining a sulfonated unhydrogenated random styrene butadiene copolymer having a sulfonation level of from about 1 to 100 meq S03H per 100 g of polymer and a sulfonated asphalt at a temperature of at least about 180 DEG C. to produce a storage stable polymer modified asphalt. Yet another is a method of making a storage stable polymer modified asphalt by combining a sulfonated unhydrogenated random styrene and butadiene copolymer having a sulfonation level of from about 1 to 100 meq S03H/100 g of polymer, and unsulfonated asphalt and a basic neutralizing agent at a temperature of from about 170 DEG C. to 185 DEG C. to produce a storage stable polymer modified asphalt. Still another is a method for making a storage stable road paving composition by cosulfonation of a blend of unhydrogenated random styrene-butadiene copolymer and an asphalt at 180 DEG -210 DEG C. The novel road paving asphaltic compositions have enhanced viscoelasticity and storage stability. The compositions can be used as binders in road paving applications. Sulfonated copolymers of random styrene-isoprene may be substituted for the sulfonated copolymers of styrene-butadiene herein.

What is claimed is: 
     
       1. A road paving binder composition, comprising: a storage stable blend of a sulfonated, unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers having a sulfonation level of from 1 to 100 meq SO 3  H/100 g of polymer and a sulfonated asphalt. 
     
     
       2. The composition of claim 1 wherein the blend is base neutralized. 
     
     
       3. The composition of claim 2 wherein the polymer is base-neutralized. 
     
     
       4. The composition of claim 1 wherein the blend has a viscosity of from about 900 to 8000 cPs at 135° C. and a softening point of at least about 45° C. 
     
     
       5. The composition of claim 1 wherein the sulfonated asphalt is produced by sulfonating an unsulfonated asphalt with from 0.1 to 5 wt % of sulfonating agent based on the weight of the starting asphalt. 
     
     
       6. A method of making a storage stable road paving binder composition, comprising: combining a sulfonated asphalt and an unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers wherein the polymer has a sulfonation level of from about 10 to 30 meq SO 3  H per 100 g of polymer at a temperature of at least about 180° C. to produce a storage stable polymer modified asphalt. 
     
     
       7. The method of claim 6 wherein the temperature is from 190° C. to 210° C. 
     
     
       8. A road paving binder composition, comprising: a storage stable blend of a sulfonated unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers having a sulfonation level of from about 1 to about 100 meq SO 3  H/100g polymer and an unsulfonated asphalt. 
     
     
       9. The composition of claim 8 wherein the blend is base-neutralized. 
     
     
       10. A method of making a storage stable road paving binder composition comprising: combining a sulfonated unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers having a sulfonation level of from about 10 to 30 meq SO 3  H/100 g of polymer, and unsulfonated asphalt at a temperature of at least 170° C. to produce a storage stable road paving binder. 
     
     
       11. The method of claim 10 wherein the temperature is from 170° C. to 1850° C. 
     
     
       12. A storage stable road paving binder composition produced by the process of (a) blending an asphalt and an unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers at sufficient temperature for a sufficient time to disperse the polymer in the asphalt; (b) maintaining the blend temperature of at least 180° C.; (c) adding a sulfonating agent in the amount of from 1 to 5 wt % based on the weight of the blend; and (d) purging the blend of step (c) with an unreactive gas at a temperature of at least about: 180° C. 
     
     
       13. The composition of claim 12, further comprising neutralizing the blend of step (c). 
     
     
       14. The composition of claim 12 wherein the temperature in steps (b) and (d) is from about 190° C. to 210° C. 
     
     
       15. The composition of claim 12 wherein the copolymer is added to the asphalt in the form of a latex containing at least 50 wt % polymer. 
     
     
       16. The composition of claim 12 wherein the blend has a viscosity of from about 900 to 8000 cPs at 135° C. and a softening point of at least 45° C. 
     
     
       17. A method of making a storage stable road paving binder composition, comprising: (a) blending an asphalt and an unhydrogenated random copolymer selected from the group consisting of styrene butadiene copolymers and styrene isoprene copolymers at sufficient temperature for a sufficient time to disperse the polymer in the asphalt; (b) maintaining the blend temperature of at least 180° C.; (c) adding a sulfonating agent in the amount of from 1 to 5 wt % based on the weight of the blend; and (d) purging the blend of step (c) with an unreactive gas at least about 180° C. 
     
     
       18. The method of claim 15 wherein the product of step (c) is neutralized. 
     
     
       19. The method of claim 16 wherein the temperature is from about 190° C. to 210° C.